Multiple sacro‐coccygeal dermoid sinuses on a Thai Ridgeback

Abstract

A 16-month-old, female entire, Thai Ridgeback was presented for evaluation of a two subcutaneous, non-painful, fluctuant masses associated with two firm tubular tracts in the soft tissue dorsal to the sacrum and proximal caudal vertebrae originating at the skin surface slightly to the right of the tail base. Physical and neurological examination was otherwise normal. Magnetic resonance imaging of the lumbosacral spine revealed two dermoid sinuses type I and type II. Surgical resection and histopathological examination confirmed the presumed diagnosis. To the authors' knowledge, the presence of two dermoid sinuses in this location has not been previously described in a Thai Ridgeback or in another dog breed in the veterinary literature. The prognosis following surgical resection appears favourable. BACKGROUNDA dermoid sinus (DS) is an embryonic/congenital development defect that results in an incomplete separation between the skin and the ectodermal neural tube. 1 A sinus tract is lined with squamous epithelium, hair follicles and sebaceous glands, with a small cutaneous opening on the dorsal midline that extends ventrally from the skin to the subarachnoid space or dura mater or ends as a blind sac at a different depth. 2,3 DSs are classified based on the degree of ventral extension (I-VI) (Figure 1). DSs are more often located in the cervical and craniothoracic regions but can also occur anywhere along the spine and even in the head. 1,[4][5][6][7][8][9][10] This disorder is encountered most commonly in Rhodesian Ridgeback dogs, but has been reported in other breeds such as Dachshund, 11 Great Pyrenees dog, 12

Diagnosis and surgical management of a type IVb dermoid sinus in a Cavalier King Charles Spaniel

“…Dermoid sinuses are well described in the Rhodesian Ridgeback breed 2 in which an autosomal dominant mutation causes the dorsal ridge and predisposes the breed to dermoid sinus formation 3 . Dermoid sinus formation has been reported in other breeds in the nasal, 4,5 cervical, 6 thoracic, 7–10 lumbosacral 11 and sacro‐coccygeal 12 regions, but rarely in the head region 13–16 . Previous case reports described dermoid sinuses in the frontal, parietal, parieto‐occipital and fronto‐occipital regions in dogs 13–16 .…”